northern raven vs rook

northern raven

noun
  • A common raven, Corvus corax. 

rook

noun
  • A European bird, Corvus frugilegus, of the crow family. 

  • A cheat or swindler; someone who betrays. 

  • mist; fog; roke 

  • A castle or other fortification. 

  • A rookie. 

  • A piece shaped like a castle tower, that can be moved only up, down, left or right (but not diagonally) or in castling. 

  • A type of firecracker used by farmers to scare birds of the same name. 

  • A trick-taking game, usually played with a specialized deck of cards. 

  • A bad deal; a rip-off. 

verb
  • To cheat or swindle. 

How often have the words northern raven and rook occurred in a corpus of books? (source: Google Ngram Viewer )